牙髓细胞DNA含量与死后经过时间的相关性

目的探讨死后不同环境温度下离体牙的牙髓细胞平均DNA含量变化与死后时间(PM I)的相关性。方法采用细胞图像分析系统(PIPS-2020),测定离体即刻至15d牙齿在低温环境(10~15℃)和高温(30~35℃)环境下牙髓细胞DNA含量变化值,并对其数据进行统计学分析。结果在不同的环境温度下,牙髓细胞DNA降解的速度有所不同,温度的升高有加速牙髓细胞DNA降解的趋势,且DNA降解存在一个平台期。低温组牙髓细胞平均DNA含量与PM I之间的相关系数r=0.953,相关指数R2=0.917;高温组的相关系数r=0.991,相关指数R2=0.971。结论牙髓细胞平均DNA含量与PM I之间具有高度相关性,测定牙髓细胞的DNA变化情况对推断3d(高温环境)或6d(低温环境)后的PM I有参考价值。

A study on the correlation between postmortem interval and DNA degradation in the human dental pulp cells

Objective To study the correlation between DNA content in dental pulp cells and postmortem interval (PMI) under different temperature. Methods Changes of DNA content in dental pulp cells under lower (10~15℃) and higher environment temperature (30~35℃) was determined at PMI from 0 to 15d by an Image Cytometry Analysis System ( PIPS-2020). The results were analyzed statistically. Results The average DNA content in dental pulp cells was reduced after death. But the decreasing rate of DNA content was different under two ambient temperatures. The average DNA content kept relatively stable within 3d PMI under higher temperature and 6d PMI under lower temperature, which was considered as a plateau period for DNA degradation in dental pulp cells. The DNA content in higher temperature decreased more quickly than in lower temperature after the plateau period. The correlation coefficient for DNA degradation in dental pulp cells was 0.953 with r~2=0.917 under lower temperature and 0.991 with r~2=0.971 under higher temperature. Conclusion There is a high correlation between decrease in the average DNA content of dental pulp cells and the PMI, The method may be used for PMI estimation after three days (at higher temperature) and six days (at lower temperature).